The drone war takes place in the shadows. As citizens, we have little idea of what killing is going on in our name, though recent leaks help paint a picture.

To dramatize both the reality and the lack of disclosure, British artist James Bridle has been chalking outlines on city street with his project Drone Shadows. The work looks like the markings for murder victims–which is part of the point–though they depict the overflying aerial vehicles.

Bridle drew the first outline in London in early 2012, and has since followed up with further drawings in Istanbul, Brighton, Washington D.C., Brisbane, Australia, Sao Paolo, Detroit and elsewhere. “In order to understand the world around us, we sometimes need to draw it out,” he says. “If you can’t really describe the world around you, you can’t fully act in it, and are made powerless. When you can describe it, you can debate and critique it. Drawing its shadow is just the first step.”

To encourage others to follow his lead, he’s created a detailed Drone Shadow Handbook, with instructions about making your own markings. Helpfully, it covers several well-known drone types (Predator, Hawk, Reaper), providing dimensions for each. “Drone Shadows should be 1:1 representations: they should be the exact dimensions of real drones, according to the measurements in the schematics here or ones you create yourself,” he says.